Charles Spurgeon Commentary John 18:28

"They lead Jesus therefore from Caiaphas into the Praetorium: and it was early; and they themselves entered not into the Praetorium, that they might not be defiled, but might eat the passover." — John 18:28 (ASV)

Then led they Jesus from Caiaphas unto the hall of judgment:

That is to say, Pilate's hall. Pilate, at that time, was probably residing in one of the old and sumptuous palaces of Herod, there holding his court during the time of the Passover.

And they themselves went not into the judgment hall, lest they should be defiled; but that they might eat the passover.

What could defile such wretches as these? Yet they were afraid of ceremonial defilement, though neither afraid nor ashamed to stain their hands with the blood of Jesus.

And it was early;

They were very eager to prove their enmity to Christ; they had spent the night, and the earliest moments of the dawn, in examining their illustrious prisoner, condemning him, and abusing him, and now they were off to Pilate.